A humble soil additive used by millions of gardeners is set to slash the cost of the most effective form of insulation for buildings. New research demonstrates that vacuum insulation panels can be made with a core of perlite – the volcanic ore “popcorn” used in horticulture to improve drainage and water retention. The material dramatically reduces the cost of the panels that are normally made by surrounding a core of fumed silica with metallized PET envelope. Initial cost savings are estimated to be at least 30%. According to Brunel University London academic Dr Harjit Singh: “Perlite also has a…